Olena Poliarus - Academia.edu (original) (raw)
Papers by Olena Poliarus
Вісник двигунобудування, 2014
Research Bulletin of NTUU Kyiv Polytechnic Institute367367112017-10-27, 2012
In this paper, the structure of NiAl-15wt.%CrB2, NiAl-15wt.%ZrB2 and NiAl-15wt.%TiB2 composite co... more In this paper, the structure of NiAl-15wt.%CrB2, NiAl-15wt.%ZrB2 and NiAl-15wt.%TiB2 composite compact materials was studied using SEM. The composites were obtained by sintering in vacuum. The phase composition was studied by XRD analysis. The effect of the diboride additives on the NiAl hardness was studied. It is shown that the initial intermetallic had a hardness of 288 HV20. At the same time, the hardness value for the NiAl-15wt.% ZrB2 composite is 349 HV20, for NiAl-15wt.%TiB2 it is 392 HV20 and for the NiAl-15wt.%CrB2 composite material it is 468 HV20.
Archives of Civil and Mechanical Engineering, Mar 2, 2023
Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of p... more Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of present-day turbine propulsion systems. The ones deposited with atmospheric plasma spraying (APS) are characterized by required low thermal conductivity, but they are unable to survive frequent thermomechanical loading and therefore their application is limited to parts remaining stationary. Expanding capability of TBCs is sought in various areas, but the one realized through modification of most proliferated apparatus used for plasma spraying (PS) (from radial to axial injection) and substituting micrometric powders with the nano-structured suspension needs least changes in the industry established procedures and offers the highest property improvement. The present experiment covered the deposition of ZrO 2-8Y 2 O 3 YSZ TBC using both atmospheric and suspension PS processes. They were performed with commercial micrometric and nano-structured YSZ (8% Y 2 O 3) powders. The coatings morphology and microstructure were characterized with 3D profilometry, scanning and transmission electron microscopy (SEM/TEM) methods. Finally, the coating's hardness and heat conductivity were measured. This complex approach allowed to state that PS of micrometric t'-ZrO 2 powder having an admixture of m-ZrO 2 phase is capable of only partial improvement in its homogenization. However, the suspension PS process of nano-structured powder eliminated any traces of the monoclinic phase from the coating. The TEM microstructure observations indicated that the suspension PS coating is built by in-flight solidified droplets as well as by the melted ones flattened on arrival. A surface layer of liquefied material on solid droplets increases their adhesion to surface asperities promoting pseudo-columnar growth of the coating. The preservation of monotonic slow increase of thermal conductivity during heating of the suspension PS coating means, that its pseudo-columnar microstructure is better suited to withstand high strains during such treatment. Keywords Yttrium-stabilized zirconia (YSZ) • Suspension plasma spraying (SPS) • Atmospheric plasma spraying (APS) • Thermal barrier coatings (TBC)
Archives of Civil and Mechanical Engineering
In this article the affiliation details for Krzysztof T. Wojciechowski were incorrectly given as ... more In this article the affiliation details for Krzysztof T. Wojciechowski were incorrectly given as 'Laser Process
Results of high temperature friction tests of Cr 2 O 3 , TiO 2 , ZrO 2 gas-thermal oxide coatings... more Results of high temperature friction tests of Cr 2 O 3 , TiO 2 , ZrO 2 gas-thermal oxide coatings was presented in this work. Coatings was obtained by plasma spraying method. Tribotechnical properties of oxides was investigated by «pin-on-disc» scheme under T = 500 °C. These investigations showed that chromium oxide possess the highest wear resistance due to formation of complex (NiCrAl) x O y oxide film on Cr 2 O 3 surface during friction process, that prevent immediate contact of coating and counter-body and decrease wear in this friction couple.
The preparation of powder agglomerates used in the plasma spray deposition processes, and especia... more The preparation of powder agglomerates used in the plasma spray deposition processes, and especially their homogeneity, turned out to be highly important at the moment when the phase ratio in the composite coatings began to differ from that in the starting materials. The present experiment was aimed at comparing the microstructure and phase composition of hot pressed or sintered NiAl and CrB2 powders. The use of SEM and XRD methods showed that only sintering leads to a reaction of the chromium diboride with the intermetallic matrix. As a result of this process, Ni0.5Cr1.5B3 phase precipitates on the CrB2 particles. Consequently, the agglomerates formed after crushing the compacts obtained by sintering are much more homogeneous than those formed by hot pressing.
The development of a new deposition method allowing to obtain thick composite coatings is of both... more The development of a new deposition method allowing to obtain thick composite coatings is of both scientifically and practical importance. The one presented in this paper is based on a negative side effect taking place during the mechanical synthesis of alloys, i.e. sticking of milled material to the surfaces of both the vial and balls. The experiment covered the comilling of NiAl (~45 μm) with 15 wt.% CrB2 (~40 μm) powders together with nickel platelets used as the substrates and steel balls. The above processing performed at 200 rpm resulted in a steady increase in the thickness of the rubbed-in buildup on the platelet surfaces allowing coatings of 4, 11, 22 and 33 μm to be produced after 4, 8, 16 and 32 hours. The OM, XRD and TEM investigations showed that such coatings are characterized by a gradient microstructure with heavily dislocated but coarser grains near the substrate and a more porous inner part formed with rounded well fused agglomerates of greatly refined crystallites...
Materials Characterization, 2020
Abstract Nickel aluminide coatings - produced using atmospheric plasma spraying method - attracte... more Abstract Nickel aluminide coatings - produced using atmospheric plasma spraying method - attracted considerable attention due to their high melting temperature and oxidation resistance. What is more, an addition of CrB2 allows to significantly increase their wear resistance. Such coatings are typically used up to 500 °C, what requires thermal stability of their microstructure. Therefore, in this paper, the in-situ TEM heating of APS-deposited NiAl coating with addition of 15 wt% of CrB2 up to 800 °C was performed in order to follow the microstructure changes and eventual phase transformations. The TEM observations backed with phase analysis showed that the amorphous veins present in the NiAl matrix of as-deposited coating transform into Ni6AlB3 phase at approaching 500 °C. On the other hand, the CrB2/NiAl interface preserved its shape and remains free from any precipitates even up to 800 °C. The ex-situ TEM microstructure observations of NiAl + CrB2 coating, carried out after high-temperature wear test (500 °C, ~15 min), showed that after it amorphous channels indeed turns crystalline. In addition, the NiAl matrix presents significantly higher dislocation density, being a result of repeated loading received during the wear test.
Materials, 2019
Metal matrix composite coatings are developed to protect parts made from materials susceptible to... more Metal matrix composite coatings are developed to protect parts made from materials susceptible to wear, like nickel alloys or stainless steel. The industry-established deposition method is presently an atmospheric plasma spraying method since it allows the production of both well-adhering and thick coatings. Alternatively, similar coatings could be produced by co-milling of ceramic and alloyed powders together with metallic plates serving as substrates. It results in mechanical embedding of the powder particles into exposed metallic surfaces required coatings. The present experiment was aimed at the analysis of microstructure of such coatings obtained using NiAl and CrB2 powders. They were loaded together with nickel and stainless steel platelets into ball mill vials and rotated at 350 rpm for up to 32 h. This helped to produce coatings of a thickness up to ~40 µm. The optical, scanning, and transmission electron microscopy observations of the coatings led to conclusion that the hig...
Archives of Civil and Mechanical Engineering, 2019
Journal of Thermal Spray Technology, 2019
The properties of plasma-sprayed composite coatings depend to a large extent on the homogenizatio... more The properties of plasma-sprayed composite coatings depend to a large extent on the homogenization of the powders used for their deposition. In order to investigate this relation, mixtures of NiAl and CrB 2 (15 and 30 wt.%) powders were prepared via an organic binder (a), hot pressing (b) or sintering (c). The obtained composite agglomerates were sprayed on cylindrical AISI 310S steel pins. Their wear resistance was assessed through a pin-ondisc dry-sliding wear test carried out at 500°C (a counterbody of NiAl coating was also deposited on AISI 310S). All the composite coatings presented strongly reduced the wear rate when compared with the reference NiAl coatings (9.8 9 10-5 mm 3 /Nm). Those with 30 wt.% CrB 2 addition and obtained via the (a), (b) and (c) routes had 3.8, 2.9 and 1.4 mm 3 /Nm 10-5 , while those with 15 wt.% CrB 2 for the same routes had 2.6, 0.9 and 0.7 mm 3 /Nm 10-5 , respectively. The least damage was present in the NiAl (15 wt.% CrB 2) coating obtained using route (c), due to the microstructure refinement already achieved at the sintering stage and the good reactive binding of CrB 2 with the coating matrix, established during plasma spraying. Increasing the CrB 2 addition up to 30 wt.% promotes crack propagation accelerating wear.
Powder Metallurgy and Metal Ceramics, 2018
The compressive yield stress and bending strength of NiAl-CrB 2 composites are studied in the 20-... more The compressive yield stress and bending strength of NiAl-CrB 2 composites are studied in the 20-800°C temperature range. The effect of the composite phase ratio and experimental temperature on the composite strength for different loading patterns is established. During tensile stresses, the introduction of 15 wt.% CrB 2 into the intermetallic is optimal to ensure the maximum bending strength of the composite at 500C. The bending strength of NiAl-15 wt.% CrB 2 composite at the experimental temperature 500°C exceeds that of the starting NiAl, by a factor of 3.
Key Engineering Materials, 2014
In this study the influence of the TiB2, ZrB2, and CrB2 additives into NiAl-intermetallics on the... more In this study the influence of the TiB2, ZrB2, and CrB2 additives into NiAl-intermetallics on their wear behavior under friction conditions at the high temperature in the pair with steel has been investigated. It was shown, that the borides additives have influenced on the wear mechanism, significantly increasing the wear resistance of composite coatings pointed out. Among the coatings studied the NiAl-15 wt. % CrB2 coating showed the best result.
Key Engineering Materials, 2016
The corrosion behavior in seawater of NiAl and NiTi intermetallics and composites based on them h... more The corrosion behavior in seawater of NiAl and NiTi intermetallics and composites based on them has been studied in this paper. It was shown that the developed composite NiTi-30 wt.% CrB2 hardly corrodes. The developed materials are meant for protect different shipbuilding details and details of hydropower equipment from aggressive sea water environments, as well as against hydro-abrasive and cavitation wear.
Proceedings of National Aviation University, 2013
Materials Science, 2016
The development of composite materials (CM) in the systems "metal-refractory compound" is one of ... more The development of composite materials (CM) in the systems "metal-refractory compound" is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C), it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3-7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl-МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С) coatings NiAl-15 wt.% CrB2 (TiB2, ZrB2).
Key Engineering Materials, 2016
In this study, the tribological characteristics of plasma thermal spray coatings are studied with... more In this study, the tribological characteristics of plasma thermal spray coatings are studied with particular interest on formation and performance of Cr, Ti and Zr oxides under dry sliding at 500 °С with Pin-On-Disc configuration against NiAl. Plain Cr2O3, TiO2 and ZrO2 coatings were tested to trace the difference between performance of original and in-situ formed oxides. Friction surfaces were examined using SEM and X-ray spectral analyses. The highest wear resistance of NiAl-CrB2 composite coatings can be related to the formation of Cr2O3 during the tribosynthesis process.
Powder Metallurgy and Metal Ceramics, 2015
The influence of chromium diboride additions on the tribotechnical characteristics of NiAl-CrB 2 ... more The influence of chromium diboride additions on the tribotechnical characteristics of NiAl-CrB 2 composite coatings in friction against a counterface made of NiAl plasma-sprayed coating is studied. The friction surfaces of the plasma-sprayed composite NiAl coatings with different chromium diboride contents (5, 15, and 30 wt.%) are examined. It is established that wear substantially depends on the amount of refractory component.
NiAl-CrB 2 із різним вмістом дибориду хрому. Проведено дослідження поверхонь тертя розроблених пл... more NiAl-CrB 2 із різним вмістом дибориду хрому. Проведено дослідження поверхонь тертя розроблених плазмових покриттів NiAl, NiAl-5% CrB 2 та NiAl-15% CrB 2. Показано, що на характер зношування суттєво впливає температура випробувань, а також кількість тугоплавкої домішки. Ключові слова: композиційні покриття, інтерметалід NiAl, диборид хрому, зносостійкість, високотемпературні трибовипробування. Рис. 5. Літ. 2. М.С. Украинец, А.П. Уманский, Е.Н. Полярус, А.В. Кущев, А.У. Стельмах ВЛИЯНИЕ ТЕМПЕРАТУРЫ ИСПЫТАНИЙ НА ТРИБОТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ КОМПОЗИЦИОННЫХ ПОКРЫТИЙ СИСТЕМЫ NiAl-CrB 2 В статье проанализировано влияние температуры испытаний на триботехнические характеристики композиционных покрытий системы NiAl-CrB 2 с различным содержанием диборида хрома. Проведены исследования поверхностей трения разработанных плазменных покрытий NiAl, NiAl-5% CrB и NiAl-15% CrB 2. Показано, что на характер износа существенно влияет температура испытаний, а также количество тугоплавкой составляющей. ...
Вісник двигунобудування, 2014
Research Bulletin of NTUU Kyiv Polytechnic Institute367367112017-10-27, 2012
In this paper, the structure of NiAl-15wt.%CrB2, NiAl-15wt.%ZrB2 and NiAl-15wt.%TiB2 composite co... more In this paper, the structure of NiAl-15wt.%CrB2, NiAl-15wt.%ZrB2 and NiAl-15wt.%TiB2 composite compact materials was studied using SEM. The composites were obtained by sintering in vacuum. The phase composition was studied by XRD analysis. The effect of the diboride additives on the NiAl hardness was studied. It is shown that the initial intermetallic had a hardness of 288 HV20. At the same time, the hardness value for the NiAl-15wt.% ZrB2 composite is 349 HV20, for NiAl-15wt.%TiB2 it is 392 HV20 and for the NiAl-15wt.%CrB2 composite material it is 468 HV20.
Archives of Civil and Mechanical Engineering, Mar 2, 2023
Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of p... more Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of present-day turbine propulsion systems. The ones deposited with atmospheric plasma spraying (APS) are characterized by required low thermal conductivity, but they are unable to survive frequent thermomechanical loading and therefore their application is limited to parts remaining stationary. Expanding capability of TBCs is sought in various areas, but the one realized through modification of most proliferated apparatus used for plasma spraying (PS) (from radial to axial injection) and substituting micrometric powders with the nano-structured suspension needs least changes in the industry established procedures and offers the highest property improvement. The present experiment covered the deposition of ZrO 2-8Y 2 O 3 YSZ TBC using both atmospheric and suspension PS processes. They were performed with commercial micrometric and nano-structured YSZ (8% Y 2 O 3) powders. The coatings morphology and microstructure were characterized with 3D profilometry, scanning and transmission electron microscopy (SEM/TEM) methods. Finally, the coating's hardness and heat conductivity were measured. This complex approach allowed to state that PS of micrometric t'-ZrO 2 powder having an admixture of m-ZrO 2 phase is capable of only partial improvement in its homogenization. However, the suspension PS process of nano-structured powder eliminated any traces of the monoclinic phase from the coating. The TEM microstructure observations indicated that the suspension PS coating is built by in-flight solidified droplets as well as by the melted ones flattened on arrival. A surface layer of liquefied material on solid droplets increases their adhesion to surface asperities promoting pseudo-columnar growth of the coating. The preservation of monotonic slow increase of thermal conductivity during heating of the suspension PS coating means, that its pseudo-columnar microstructure is better suited to withstand high strains during such treatment. Keywords Yttrium-stabilized zirconia (YSZ) • Suspension plasma spraying (SPS) • Atmospheric plasma spraying (APS) • Thermal barrier coatings (TBC)
Archives of Civil and Mechanical Engineering
In this article the affiliation details for Krzysztof T. Wojciechowski were incorrectly given as ... more In this article the affiliation details for Krzysztof T. Wojciechowski were incorrectly given as 'Laser Process
Results of high temperature friction tests of Cr 2 O 3 , TiO 2 , ZrO 2 gas-thermal oxide coatings... more Results of high temperature friction tests of Cr 2 O 3 , TiO 2 , ZrO 2 gas-thermal oxide coatings was presented in this work. Coatings was obtained by plasma spraying method. Tribotechnical properties of oxides was investigated by «pin-on-disc» scheme under T = 500 °C. These investigations showed that chromium oxide possess the highest wear resistance due to formation of complex (NiCrAl) x O y oxide film on Cr 2 O 3 surface during friction process, that prevent immediate contact of coating and counter-body and decrease wear in this friction couple.
The preparation of powder agglomerates used in the plasma spray deposition processes, and especia... more The preparation of powder agglomerates used in the plasma spray deposition processes, and especially their homogeneity, turned out to be highly important at the moment when the phase ratio in the composite coatings began to differ from that in the starting materials. The present experiment was aimed at comparing the microstructure and phase composition of hot pressed or sintered NiAl and CrB2 powders. The use of SEM and XRD methods showed that only sintering leads to a reaction of the chromium diboride with the intermetallic matrix. As a result of this process, Ni0.5Cr1.5B3 phase precipitates on the CrB2 particles. Consequently, the agglomerates formed after crushing the compacts obtained by sintering are much more homogeneous than those formed by hot pressing.
The development of a new deposition method allowing to obtain thick composite coatings is of both... more The development of a new deposition method allowing to obtain thick composite coatings is of both scientifically and practical importance. The one presented in this paper is based on a negative side effect taking place during the mechanical synthesis of alloys, i.e. sticking of milled material to the surfaces of both the vial and balls. The experiment covered the comilling of NiAl (~45 μm) with 15 wt.% CrB2 (~40 μm) powders together with nickel platelets used as the substrates and steel balls. The above processing performed at 200 rpm resulted in a steady increase in the thickness of the rubbed-in buildup on the platelet surfaces allowing coatings of 4, 11, 22 and 33 μm to be produced after 4, 8, 16 and 32 hours. The OM, XRD and TEM investigations showed that such coatings are characterized by a gradient microstructure with heavily dislocated but coarser grains near the substrate and a more porous inner part formed with rounded well fused agglomerates of greatly refined crystallites...
Materials Characterization, 2020
Abstract Nickel aluminide coatings - produced using atmospheric plasma spraying method - attracte... more Abstract Nickel aluminide coatings - produced using atmospheric plasma spraying method - attracted considerable attention due to their high melting temperature and oxidation resistance. What is more, an addition of CrB2 allows to significantly increase their wear resistance. Such coatings are typically used up to 500 °C, what requires thermal stability of their microstructure. Therefore, in this paper, the in-situ TEM heating of APS-deposited NiAl coating with addition of 15 wt% of CrB2 up to 800 °C was performed in order to follow the microstructure changes and eventual phase transformations. The TEM observations backed with phase analysis showed that the amorphous veins present in the NiAl matrix of as-deposited coating transform into Ni6AlB3 phase at approaching 500 °C. On the other hand, the CrB2/NiAl interface preserved its shape and remains free from any precipitates even up to 800 °C. The ex-situ TEM microstructure observations of NiAl + CrB2 coating, carried out after high-temperature wear test (500 °C, ~15 min), showed that after it amorphous channels indeed turns crystalline. In addition, the NiAl matrix presents significantly higher dislocation density, being a result of repeated loading received during the wear test.
Materials, 2019
Metal matrix composite coatings are developed to protect parts made from materials susceptible to... more Metal matrix composite coatings are developed to protect parts made from materials susceptible to wear, like nickel alloys or stainless steel. The industry-established deposition method is presently an atmospheric plasma spraying method since it allows the production of both well-adhering and thick coatings. Alternatively, similar coatings could be produced by co-milling of ceramic and alloyed powders together with metallic plates serving as substrates. It results in mechanical embedding of the powder particles into exposed metallic surfaces required coatings. The present experiment was aimed at the analysis of microstructure of such coatings obtained using NiAl and CrB2 powders. They were loaded together with nickel and stainless steel platelets into ball mill vials and rotated at 350 rpm for up to 32 h. This helped to produce coatings of a thickness up to ~40 µm. The optical, scanning, and transmission electron microscopy observations of the coatings led to conclusion that the hig...
Archives of Civil and Mechanical Engineering, 2019
Journal of Thermal Spray Technology, 2019
The properties of plasma-sprayed composite coatings depend to a large extent on the homogenizatio... more The properties of plasma-sprayed composite coatings depend to a large extent on the homogenization of the powders used for their deposition. In order to investigate this relation, mixtures of NiAl and CrB 2 (15 and 30 wt.%) powders were prepared via an organic binder (a), hot pressing (b) or sintering (c). The obtained composite agglomerates were sprayed on cylindrical AISI 310S steel pins. Their wear resistance was assessed through a pin-ondisc dry-sliding wear test carried out at 500°C (a counterbody of NiAl coating was also deposited on AISI 310S). All the composite coatings presented strongly reduced the wear rate when compared with the reference NiAl coatings (9.8 9 10-5 mm 3 /Nm). Those with 30 wt.% CrB 2 addition and obtained via the (a), (b) and (c) routes had 3.8, 2.9 and 1.4 mm 3 /Nm 10-5 , while those with 15 wt.% CrB 2 for the same routes had 2.6, 0.9 and 0.7 mm 3 /Nm 10-5 , respectively. The least damage was present in the NiAl (15 wt.% CrB 2) coating obtained using route (c), due to the microstructure refinement already achieved at the sintering stage and the good reactive binding of CrB 2 with the coating matrix, established during plasma spraying. Increasing the CrB 2 addition up to 30 wt.% promotes crack propagation accelerating wear.
Powder Metallurgy and Metal Ceramics, 2018
The compressive yield stress and bending strength of NiAl-CrB 2 composites are studied in the 20-... more The compressive yield stress and bending strength of NiAl-CrB 2 composites are studied in the 20-800°C temperature range. The effect of the composite phase ratio and experimental temperature on the composite strength for different loading patterns is established. During tensile stresses, the introduction of 15 wt.% CrB 2 into the intermetallic is optimal to ensure the maximum bending strength of the composite at 500C. The bending strength of NiAl-15 wt.% CrB 2 composite at the experimental temperature 500°C exceeds that of the starting NiAl, by a factor of 3.
Key Engineering Materials, 2014
In this study the influence of the TiB2, ZrB2, and CrB2 additives into NiAl-intermetallics on the... more In this study the influence of the TiB2, ZrB2, and CrB2 additives into NiAl-intermetallics on their wear behavior under friction conditions at the high temperature in the pair with steel has been investigated. It was shown, that the borides additives have influenced on the wear mechanism, significantly increasing the wear resistance of composite coatings pointed out. Among the coatings studied the NiAl-15 wt. % CrB2 coating showed the best result.
Key Engineering Materials, 2016
The corrosion behavior in seawater of NiAl and NiTi intermetallics and composites based on them h... more The corrosion behavior in seawater of NiAl and NiTi intermetallics and composites based on them has been studied in this paper. It was shown that the developed composite NiTi-30 wt.% CrB2 hardly corrodes. The developed materials are meant for protect different shipbuilding details and details of hydropower equipment from aggressive sea water environments, as well as against hydro-abrasive and cavitation wear.
Proceedings of National Aviation University, 2013
Materials Science, 2016
The development of composite materials (CM) in the systems "metal-refractory compound" is one of ... more The development of composite materials (CM) in the systems "metal-refractory compound" is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C), it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3-7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl-МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С) coatings NiAl-15 wt.% CrB2 (TiB2, ZrB2).
Key Engineering Materials, 2016
In this study, the tribological characteristics of plasma thermal spray coatings are studied with... more In this study, the tribological characteristics of plasma thermal spray coatings are studied with particular interest on formation and performance of Cr, Ti and Zr oxides under dry sliding at 500 °С with Pin-On-Disc configuration against NiAl. Plain Cr2O3, TiO2 and ZrO2 coatings were tested to trace the difference between performance of original and in-situ formed oxides. Friction surfaces were examined using SEM and X-ray spectral analyses. The highest wear resistance of NiAl-CrB2 composite coatings can be related to the formation of Cr2O3 during the tribosynthesis process.
Powder Metallurgy and Metal Ceramics, 2015
The influence of chromium diboride additions on the tribotechnical characteristics of NiAl-CrB 2 ... more The influence of chromium diboride additions on the tribotechnical characteristics of NiAl-CrB 2 composite coatings in friction against a counterface made of NiAl plasma-sprayed coating is studied. The friction surfaces of the plasma-sprayed composite NiAl coatings with different chromium diboride contents (5, 15, and 30 wt.%) are examined. It is established that wear substantially depends on the amount of refractory component.
NiAl-CrB 2 із різним вмістом дибориду хрому. Проведено дослідження поверхонь тертя розроблених пл... more NiAl-CrB 2 із різним вмістом дибориду хрому. Проведено дослідження поверхонь тертя розроблених плазмових покриттів NiAl, NiAl-5% CrB 2 та NiAl-15% CrB 2. Показано, що на характер зношування суттєво впливає температура випробувань, а також кількість тугоплавкої домішки. Ключові слова: композиційні покриття, інтерметалід NiAl, диборид хрому, зносостійкість, високотемпературні трибовипробування. Рис. 5. Літ. 2. М.С. Украинец, А.П. Уманский, Е.Н. Полярус, А.В. Кущев, А.У. Стельмах ВЛИЯНИЕ ТЕМПЕРАТУРЫ ИСПЫТАНИЙ НА ТРИБОТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ КОМПОЗИЦИОННЫХ ПОКРЫТИЙ СИСТЕМЫ NiAl-CrB 2 В статье проанализировано влияние температуры испытаний на триботехнические характеристики композиционных покрытий системы NiAl-CrB 2 с различным содержанием диборида хрома. Проведены исследования поверхностей трения разработанных плазменных покрытий NiAl, NiAl-5% CrB и NiAl-15% CrB 2. Показано, что на характер износа существенно влияет температура испытаний, а также количество тугоплавкой составляющей. ...